George Harrisonwas recording steadily at the studio in his English country estate until nearly the day he died in 2001.

“He loved to record, he was always doing more and more demos at night,” says his widow, Olivia Harrison. “But he’d always say, ‘I’ll never finish them. I’ll have to give them to (producer) Jeff Lynne (to finish).’ He knew he was going to be in his garden in the daytime, so they wouldn’t get done. But he was discovering the singer-songwriter thing again and really doing a lot of recording. He was just getting to the point of getting some sessions together. Sadly, time ran out.”

Now, Olivia Harrison and a few trusted collaborators, including Giles Martin, the son of Beatles producer George Martin, are going through the guitarist’s massive archive and bringing the best of it to the public. The first in what is projected to be a series of recordings is due out May 1, “Early Takes: Volume 1” (UMe), a collection of mostly acoustic demos documenting the early days of Harrison’s solo career. It will accompany the release on DVD and Blu-Ray of Martin Scorsese’s 2011 Harrison documentary, “Living in the Material World.”

“Early Takes” focuses on the era around the guitarist’s 1970 solo debut, “All Things Must Pass,” including demos or early takes of the title song, “My Sweet Lord,” “Behind That Locked Door,” “Awaiting On You All,” “Run of the Mill” and “I’d Have You Any Time” (cowritten with Bob Dylan). Another gem is an acoustic version of the then-decade-old Everly Brothers hit “Let It Be Me.”

In the documentary, producer Phil Spector says he was stunned to find Harrison had “hundreds” of unreleased tracks when the two began working on “All Things Must Pass.” And perfectionist that he was, Harrison left behind alternate versions of countless songs. Among the documentary’s bonus footage is a scene showing Giles and George Martin seated in front of a mixing board with Harrison’s son, Dhani. They pull up a version of Harrison’s Beatles hit “Here Comes the Sun” and play a previously unheard guitar solo by the songwriter.

“I never even knew about that,” Dhani Harrison remarks as he hears his father’s guitar-playing pour through the speakers.

There’s plenty more where that came from, as Olivia Harrison and Giles Martin describe in an interview:

Q: Did the Scorsese documentary meet your expectations?

Olivia Harrison: It’s so rich, it so captured a deep part of George. Maybe some years from now I may think of something I wish was in it. But for now, as Dhani said, ‘You’re off the hook, mom.’ I do feel like that. I was doubtful, before I met Marty, that anyone would be able to capture this part of George that was so unique, so different, the deep part of him. I thought that side was too private, too personal, but Marty managed to bring it out. So I’m grateful he did.

Q: Did you have the final say on what went into the documentary?

OH: No, not really. Marty thought really long and hard before even accepting to do this, because he needed to express what he thought all this material meant, what the story was. There were times when I was emotionally not ready to put things out into the public. We’d have conversations about it, and he’d say why it needed to be in there. It always made sense. He never wanted to do anything that would hurt anyone. We didn’t want to be flinching about something 10 years down the line over this. It was a good balance. But Marty pretty much got to do what he wanted to do.

Q: George said after the “Beatles Anthology” came out in the ‘90s that he wanted to do his own documentary one day, right?

OH: He did say, “I want to do my anthology.” When you have four people you have four different perceptions. All of them were interested in different things, and George had a different attitude toward some subjects. He was into Indian classical music, meditation, things he thought were important in life to help you get through the madness. Those things he wanted to express. He had a list of things that he wanted to do. This was one of them. In fact, he had a note -- I shouldn’t say this, but I will – he had this piece of paper saying, “Exploring my own twisted mind, Part One.” That would’ve been his title for the first half of the documentary. He wanted to share certain things with people. So I felt pretty free to follow through on this project.

Q: Did any of the material in the documentary surprise you?

OH: It surprised me that Marty chose a certain body of music that would be a narrative for George’s entire life. It wasn’t just linear, we didn’t go through the music of the ‘80s and ‘90s. Outside of maybe one or two things, he didn’t use any music beyond 1973, and that was a surprise.

Q: Do you feel some more of George’s later music should’ve been in there?

OH: No, because it was really rich what Marty did. He uses the music to take you out to sea, and then he leaves you there in this very deep water. He takes you to a place you don’t expect, and not everybody wants to go there. But that’s what he does. I respect him for that, and I think it was the right thing to do. The most surprising thing about the documentary was that it doesn’t end where you expect. It’s about life, but it’s also about death. Living and dying. It doesn’t leave you where you expected.

Giles Martin: Musically, it’s not chronological. The music reflects George’s personality and what he was thinking at the time, which is more interesting and makes it more timeless in a way.

Q: How did the CD of rarities come together?

OH: There was no plan. It was very ambitious just to do the documentary, dealing with an archive of ephemera, all these images, and the music. Marty was very interested in George’s creative process. When you hear “My Sweet Lord” take one, Marty wanted to know where did it go from there? To hear that is very revealing, aside from being an intimate experience for the listener. You can imagine George sitting on a chair singing and playing that song. It’s very intimate and it’s also revealing about the creative process.

GM: He sings beautifully. There is something different about a take that wasn’t designed to be the master take that has an excitement about it. When you think about “My Sweet Lord” or “All Things Must Pass,” that was the first time he was playing those songs with a band. It was just a three-piece band, but you get an energy that doesn’t come when things are more considered down the line. It’s like falling in love for the first time. You can’t duplicate that in subsequent takes.

OH: I was just overwhelmed with tapes. I still am (laughs). There was a huge amount of material we listened to for the director to decide what we could offer. We had reel-to-reel tapes of people up all night talking, hanging out, business meetings, demos, George and John (Lennon) working together, George’s mother singing. For a year, Giles and (recording engineer) Paul Hicks were here at George’s studio plowing through all these things that we thought Marty could use or might use. Marty was very specific about what drives the narrative. My goal was to make an archive parallel to the film.

GM: We were talking at the Beatles’ “Love” show (in Las Vegas a few years ago), and Olivia said, “We’ve got this project coming up. We have all these tapes, and a lot hasn’t been listened to.” So the task was working through it all. You get very excited when you see a tape box marked, “George, Eric (Clapton), Ringo (Starr) and Klaus (Voorman),” and then you listen and realize it’s just hours of them chatting in the studio. But other times you stumble across something really great. You are digging for gold, and there was a lot there.

Q: How did you focus the material for the CD?

GM: This collection reflects where we are at the moment. There is more we discovered. But we wanted to link this disc to the documentary. The feel of it has a nice timeline that reflects the work Marty did. Olivia’s mission and therefore my mission was to steer or inspire people away from the records and open a door to George’s creative process. We didn’t want to jump around too much. The key with this disc is to show his acoustic guitar playing and voice, as a singer-songwriter, essentially. He loved singer-songwriters, people like Bob Dylan. That’s where he took his inspiration. But people don’t often think of him like that, so it’s pretty exciting to present him this way.

Q: Did you think of broadening the scope?

OH: Initially I thought it could be a two-disc thing, but some things don’t go together. He sang a lot of songs during this time, some very obscure, by people like Nina Simone and this local girl Charlie Dore. But they didn’t really mesh, didn’t fit. We didn’t want a nine-CD set. We settled on these very intimate songs, that were so important to him at the beginning of his solo career, his emergence as a solo artist. That’s what we’re trying to present here, that particular period of his life.

Q: Did George consider putting out some of these more stripped-down recordings in his lifetime?

OH: Yeah, but he didn’t have time. He was gathering up all the bootlegs. At one time he had his engineer, Ken Scott, putting together all his bootlegs. They were piled high. He was well aware that there were people who wanted to hear some of them. But he wouldn’t ever do it to compete in the marketplace. He wouldn’t just throw it out there. He might have been a little shy about some of these demos, even from later in the ‘80s and ‘90s. … (The acoustic demo for) “Run of the Mill” was one of my favorite things. I would always say that to him. “Just play and sing and put it out because it’s beautiful.” “Really?” he’d say. “Yeah.” I think we could’ve talked him into it if we’d had more time.

Q: Will there be subsequent volumes of rarities?

OH: It would be nice. That’s why we called it “Volume One.” George wouldn’t have put just anything out, he didn’t like to scrape the bottom of the barrel. But there are things far from the bottom that we’ll put out later down the line.